Trying to digest news about my dad, really scared and struggling :(

My dad just went for prostate tests and scans in February this year, they found a lump in his bowel which turned out to be cancer. They removed it early March and he now has a permanent colostomy bag. He had never been in hospital before and albeit a big operation, he has coped well and is managing his bag. We had follow up scans and after seeing his consultant a few weeks after we have been told it has spread to his liver and is not curable. My mum had to have half her kidney removed last Wednesday because of a cancerous tumor and this was the same day as my dad's oncologist appointment. So, while she was under the knife, we got the news that without treatment he has 3-6 months to live or with 12, maybe 18 months! He also has DPYD gene in his blood so they can only give 50% of the chemo initially because his body works struggle to break it down and the side effects would be really bad and could be fatal. My heart is broken for him, my mum who has just got out of hospital after her operation and who also has heart failure after sepsis triggered her AF in December and me :( I'm the oldest of 4 and the only daughter and I don't know how to cope with this. Every morning I feel sick and I can't stop crying, I'm worried what he is now going to have to go through and how long he's got. He's 73 and just retired in February, he is well at the moment and is loving doing his garden. I also have my first grandchild coming in a few weeks, I'm excited but also so gutted about this situation, I can't be how I want to be in terms of excitement. I really don't know how to cope with this, I'm trying to be so positive for my parents, saying we'll put the brakes on this bugger, you'll he here for a good while yet etc, but I'm scared, really scared :( Any one been through this or had treatment with the DPYD gene, any advise, support would be so much appreciated xx